1. Field of the Invention
This invention relates a method and apparatus for spraying liquids and, more particularly, to a portable sprayer that includes a detachable electric pumping module and a manual back-up pump.
2. Description of the Related Art
A common item on the market today is a container that is manufactured and sold for spraying liquids. Generally, liquids are sprayed to atomize or to produce fine droplets in the air that impinge on a surface. The number of applications for liquids that are dispensed by spraying is virtually unlimited.
For this reason, many liquids are sold in containers that have an attached hand operated sprayer. The sprayer has a trigger or lever which, when manually activated, atomizes or dispenses liquid in small droplets. These manually-activated sprayers require the user to sequentially squeeze a lever or a trigger. To maintain a uniform spray pattern, a user must operate the lever or trigger rapidly while at the same time moving the container, if a large area is to be covered.
Many liquids are sold in bottles with a removable cap so that a sprayer can be attached to the container with the idea that the hand-held sprayer can be repeatedly used for different containers.
U.S. Pat. No. 7,032,841 discloses a hand-held battery power sprayer assembly having a container and a body. The sprayer assembly also includes a battery powered pump connected in series to a switch and a battery. The switch is actuated by a trigger. A passive check valve member normally closes a passageway preventing fluid flow from the container into the body. The check valve member is displaceable to permit air flow into the container.
U.S. Pat. No. 5,716,007 discloses a battery operated, hand-held fluid dispenser. The dispenser includes a supply container, a pump and discharge unit, and a discharge nozzle. The pump includes a removable battery powered pump drive unit.
U.S. Patent Publication No. 2006/0289679 discloses an interchangeable liquid sprayer that is removably attached to a liquid reservoir. The sprayer includes a discharge nozzle, a manually or electrically powered pump and an actuation mechanism for the pump. The sprayer also includes a quick-release coupling means for attaching the sprayer to a complementary quick-release coupling means fitted to the product reservoir.
Many sprayers are portable home and garden sprayers. Such sprayers are known to include a tank and a manual pumping device threadedly secured to the top of the tank. Such sprayers include “backpack” sprayers that are hand carried or supported by one shoulder strap or on the back in a backpack manner. These sprayers are usually provided with a pump that dispenses liquid from a relatively small volume container and forces the liquid through a manually controlled wand.
U.S. Pat. No. 5,752,661 discloses a backpack sprayer for spraying liquids. The sprayer includes an on board battery that drives a motor/pump assembly for pumping liquid through a manually controlled wand for spraying.
U.S. Pat. No. 4,651,903 discloses a sprayer apparatus having a molded container with a back support panel that is intended for use in abutting relation with the back of a user. The apparatus includes a centrally disposed pressure vessel within the container. The pressure vessel includes a check valve for liquids that enter the vessel. The pressure vessel communicates with a motor operated pump. The motor operated pump replaces a conventional manual pump to pressurize the vessel and direct liquid from the container to a sprayer.
U.S. Pat. No. 5,671,884 discloses an improved backpack sprayer. The sprayer includes a supply tank, an expandable accumulator, a pump mechanism, an intake valve, a discharge valve, and a spray wand with a nozzle. The pump mechanism is positioned adjacent to the bottom of the tank. The pump mechanism pumps fluid from the supply tank to the accumulator. The intake valve enables unidirectional flow from the pump to the accumulator. Fluid is discharged through the discharge valve into the spray wand and nozzle.
A key problem with conventional home and garden sprayers is that the manual pumping device requires the user to manually pump air into the tank to build-up sufficient air pressure within the air space above the liquid to be dispensed. Typically, these manual pumping devices require numerous manual pumping strokes to spray the liquids for just a few seconds. Additional manual pumping is required to re-pressurize the tank for further spraying. The pumping and spraying procedure is continued until the spraying operation is completed. It is evident that this procedure is physically exhausting for the user, is difficult to use, and is very impractical and antiquated.
One approach to solving the problem is elimination of the manual pumping device. U.S. Patent Publication No. 2006/0102245 discloses a pumpless handheld sprayer for use in the lawn and the garden. The sprayer includes a tank with an internal cavity for holding liquids for spraying and a canister that includes pressurized gas. The sprayer also includes a spray wand and a nozzle assembly. The pressurized gas canister communicates with the tank cavity, to pressurize the cavity to force the liquid through the nozzle assembly and spray wand.
Another approach utilizes a battery-operated pump. U.S. Pat. No. 4,925,105 discloses a rechargeable garden sprayer. The sprayer includes a container, a lower suction tube, and an inlet. The inlet cooperates internally with the main body of the container such that liquid poured in through the inlet flows to the container. The garden sprayer also includes, a power unit including a closed-type battery, a socket, a pump, a switch, and a nozzle tube. The nozzle tube is telescopic.
U.S. Pat. No. 3,993,245 discloses a spraying device that includes a spray tank connected through a spray valve to one or more spray nozzles. The spray tank communicates with a charging valve. The charging valve includes means adapted to provide a substantially fluid-tight seal between a container and the charging valve, container attachment means, and container puncturing means.
U.S. Pat. No. 5,695,121 discloses a self contained portable sprayer system that includes a tank for receiving a fluid mixture. The system includes a cyclic air pump that forces air into the tank. The system also includes a pressure release valve that is positioned on the top portion of the tank.
U.S. Pat. No. 6,135,361 discloses a garden sprayer for spraying liquids such as pesticides, fertilizers, and herbicides. The garden sprayer includes a housing holding a reservoir, a conduit, and a pump. The conduit includes a free outer end. A spray nozzle is coupled to the free outer end of the conduit. The spray nozzle has a trigger with a switch for selectively actuating the pump.
A disadvantage with many portable home and garden sprayers is the possibility of the user over pressurizing the tank causing the tank to rupture and possibly injuring the user. Consequently, many sprayers include conventional pressure relief devices.
U.S. Pat. No. 5,931,207 discloses a portable home and garden sprayer that includes a tank having a conventional air pressure gauge and a pressure relief valve. The sprayer also includes a hand held compressed air power unit. The hand held compressed air power unit includes a housing and an air compressor that communicates with the tank. The air compressor directs air into the tank to spray continuously until the tank empties.
U.S. Pat. No. 6,145,711 discloses a portable sprayer having a tank, a head portion, and a pump unit. The pump unit is powered by a motor to pressurize the tank. The pump unit includes a switch that is actuated when the tank pressure gets below a certain threshold to activate the motor. The sprayer also includes a pressure relief device.
U.S. Pat. No. 6,109,548 discloses a sprayer system that has a reservoir, a manual pump, an electric motor, a battery, and an air compressor. The electric motor and the compressor are mounted within an indentation of the reservoir. The electric motor operates the air compressor whenever the air pressure within the reservoir drops below a predetermined level when a pressure switch is closed. When the air pressure within the reservoir rises above a predetermined level, the electric motor is deactivated thereby preventing the reservoir from becoming over-pressurized. The manual pump may be utilized when the electric pump fails or the battery becomes discharged.